Drawing on some 30 years’ experience in the UK and Central Europe, the author offers four assertions, three about education generally and the fourth that of the title. There the case is argued that statistics is a branch of logic, and therefore should be taught by experts in such subjects as philosophy and law and not exclusively by athematicians. Education in both Statistics and these other subjects would profit in consequence.

The eulachon (Thaleichthys pacificus), a small anadromous smelt (Family Osmeridae) found only along the Northwest Pacific Coast, is poorly understood. Many spawning populations have suffered declines but as their historic status is relatively unknown and the fisheries poorly documented, it is difficult to study the contributing factors. This thesis provides a survey of eulachon fisheries throughout its geographical range and three analyses aimed at improving our understanding of past and present fisheries, coast-wide abundance status, and the factors which may be impacting these populations. An in-depth view of the Nuxalk Nation eulachon fishery on the Bella Coola River, Central Coast, BC, is provided. The majority of catches were used for making eulachon grease, a food item produced by First Nations by fermenting, then cooking the fish to release the grease. Catch statistics were kept yearly from 1945-1989 but have since, rarely been recorded. Using traditional and local ecological knowledge, catches were reconstructed based on estimated annual grease production. Run size trends were also created using local Fisheries Officers and Nuxalk interview comments. A fuzzy logic expert system was designed to estimate the relative abundance of fifteen eulachon systems. The expert system uses catch data to determine the exploitation status of a fishery and combines it with other data sources (e.g., CPUE) to estimate an abundance status index. The number of sources depended on the existing data and varied from one to eight. Using designed heuristic rules and by adjusting weighting parameters a final index was produced. Results suggest that there have been recent and extended declines in several eulachon rivers particularly the Klamath, California; Bella Coola, BC; Wannock, BC; and Kitimat, BC. Seven of the fifteen abundance time-series were used to evaluate the potential relationships between the declines and some of the factors that impact eulachon. Results suggest increases in shrimp and hake catches, seal and sea lion abundance, and sea surface temperatures were weakly associated with the declines. But contrary to expectations, adult hake biomass showed a positive association with four eulachon relative abundance time-series, suggesting that common environmental factors influenced both species.

The main subject of this thesis is a change point detection in stationary vector autoregressions. Various test statistics are proposed for the retrospective break point detection in the parameters of such models, in particular, the derivation of their asymptotic distribution under the null hypothesis of no change. Testing procedures are based on the maximum like- lihood principle and are derived under normality, nevertheless the asymptotic results are valid for broader class of distributions and involve also the models with certain form of dependence. Simulation studies document the quality of the results.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesse trabalho apresentamos a função e determinamos a natureza das convenções e hipóteses para os fundamentos científicos segundo a corrente convencionalista que surgiu na França na virada do século XIX para o XX, composta por Henri Poincaré, Pierre Duhem e Édouard Le Roy. Além disso, analisamos a relação que as convenções e hipóteses podem estabelecer com teses metafísicas através dos critérios utilizados pelos cientistas para determinar a preferência por certas teorias. Para isso, promovemos uma interpretação imanente das obras publicadas entre 1891 e 1905. Como resultado, revelamos que os autores, apesar de serem classificados como pertencentes a uma mesma corrente, não possuem apenas posições comuns, mas também divergências. Poincaré e Le Roy concordam que as convenções geométricas são escolhidas de acordo com o critério de conveniência. Contudo, eles discordam sobre o valor que a conveniência agrega ao conhecimento científico. Em relação aos fenômenos naturais, os três autores concordam que a realidade não pode ser descrita univocamente por um mesmo conjunto de convenções e hipóteses. Porém, Poincaré e Duhem acreditam que há critérios que tornam umas teorias mais satisfatórias que outras. Analisamos os critérios experimentais, racionais e axiológicos que justificam a satisfação dos cientistas com certas teorias e apontamos como estes critérios se relacionam com a metafísica. Concluímos que os convencionalistas, mesmo que cautelosamente e de modo implícito, buscaram se aproximar da metafísica com o intuito de justificar a própria atividade científica. / In this work, we present the function and we determine the nature of conventions and hypotheses for the scientific foundations according with the conventionalist doctrine that arose in France during the turning of the XIX century to the XX. The doctrine was composed by Henri Poincaré, Pierre Duhem and Édouard Le Roy. Moreover, we analyze the relation that conventions and hypotheses can establish with metaphysical thesis through criteria used by scientists in order to determine the preference for certain theories. Thereunto, we promote an immanent interpretation of published works between 1891 and 1905. As result, we reveal that the authors, though being classified as belonging to the same doctrine, don't have only common grounds, but also divergences. Poincaré and Le Roy agree that geometrical conventions are chosen in accordance with convenience criteria. However, they disagree about the value convenience aggregate to scientific knowledge. In regards to natural phenomena, the three authors agree that reality can't be described univocally by the same set of conventions and hypotheses. Yet, Poincaré and Duhem both believe that there are experimental, rational and axiological criteria that justify scientists satisfaction with certain theories and we indicate how those criteria are related with metaphysics. We conclude that conventionalists, even if warily and implicitly, searched to approach metaphysics in order to justify scientific activity.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesse trabalho apresentamos a função e determinamos a natureza das convenções e hipóteses para os fundamentos científicos segundo a corrente convencionalista que surgiu na França na virada do século XIX para o XX, composta por Henri Poincaré, Pierre Duhem e Édouard Le Roy. Além disso, analisamos a relação que as convenções e hipóteses podem estabelecer com teses metafísicas através dos critérios utilizados pelos cientistas para determinar a preferência por certas teorias. Para isso, promovemos uma interpretação imanente das obras publicadas entre 1891 e 1905. Como resultado, revelamos que os autores, apesar de serem classificados como pertencentes a uma mesma corrente, não possuem apenas posições comuns, mas também divergências. Poincaré e Le Roy concordam que as convenções geométricas são escolhidas de acordo com o critério de conveniência. Contudo, eles discordam sobre o valor que a conveniência agrega ao conhecimento científico. Em relação aos fenômenos naturais, os três autores concordam que a realidade não pode ser descrita univocamente por um mesmo conjunto de convenções e hipóteses. Porém, Poincaré e Duhem acreditam que há critérios que tornam umas teorias mais satisfatórias que outras. Analisamos os critérios experimentais, racionais e axiológicos que justificam a satisfação dos cientistas com certas teorias e apontamos como estes critérios se relacionam com a metafísica. Concluímos que os convencionalistas, mesmo que cautelosamente e de modo implícito, buscaram se aproximar da metafísica com o intuito de justificar a própria atividade científica. / In this work, we present the function and we determine the nature of conventions and hypotheses for the scientific foundations according with the conventionalist doctrine that arose in France during the turning of the XIX century to the XX. The doctrine was composed by Henri Poincaré, Pierre Duhem and Édouard Le Roy. Moreover, we analyze the relation that conventions and hypotheses can establish with metaphysical thesis through criteria used by scientists in order to determine the preference for certain theories. Thereunto, we promote an immanent interpretation of published works between 1891 and 1905. As result, we reveal that the authors, though being classified as belonging to the same doctrine, don't have only common grounds, but also divergences. Poincaré and Le Roy agree that geometrical conventions are chosen in accordance with convenience criteria. However, they disagree about the value convenience aggregate to scientific knowledge. In regards to natural phenomena, the three authors agree that reality can't be described univocally by the same set of conventions and hypotheses. Yet, Poincaré and Duhem both believe that there are experimental, rational and axiological criteria that justify scientists satisfaction with certain theories and we indicate how those criteria are related with metaphysics. We conclude that conventionalists, even if warily and implicitly, searched to approach metaphysics in order to justify scientific activity.

Ao realizar testes de hipóteses simultâneos espera-se que a decisões obtidas neles sejam logicamente consistentes entre si. Neste trabalho, verifica-se sob quais condições testes de Bayes simultâneos atendem às condições lógicas isoladamente ou em conjunto. Demonstra-se que as restrições para que os testes simultâneos atendam essas condições isoladamente são bastante intuitivas. No entanto, ao tentar obedecer as condições conjuntamente, perde-se otimalidade. Além disso, avalia-se a relação entre esses testes de Bayes simultâneos e os testes gerados por estimadores, isto é, mostra-se que, sob algumas condições, tomar uma decisão baseado em um estimador de Bayes é equivalente a tomar uma decisão baseada em um teste de Bayes. Por fim, mostra-se que, se tomamos uma decisão baseada em Estimadores de Máxima Verossimilhança, então essa decisão deve ser igual à tomada por um teste de Bayes e concluímos que essas decisões são admissíveis e obedecem ao Princípio da Verossimilhança. / When performing simultaneous hypotheses testing is expected that the decisions obtained therein are logically consistent with each other. In this work, we find restrictions under which simultaneous Bayes tests meet logical conditions separately or jointly. It is shown that the conditions for the simultaneous tests meet these conditions alone are quite intuitive. However, when trying to obey the conditions jointly, we lose optimality. Furthermore, we evaluate the relationship between these tests and simultaneous Bayes tests generated by estimators, ie, we show that, under some conditions, to choose an estimator based on Bayes decision is equivalent to choosing a decision based on a Bayes test. Finally, we show that if we take a decision based on Maximum Likelihood Estimators, then that decision should be equal to taking a Bayes test and concluded that these decisions are admissible and obey the Likelihood Principle.

The eulachon (Thaleichthys pacificus), a small anadromous smelt (Family Osmeridae) found only along the Northwest Pacific Coast, is poorly understood. Many spawning populations have suffered declines but as their historic status is relatively unknown and the fisheries poorly documented, it is difficult to study the contributing factors. This thesis provides a survey of eulachon fisheries throughout its geographical range and three analyses aimed at improving our understanding of past and present fisheries, coast-wide abundance status, and the factors which may be impacting these populations. An in-depth view of the Nuxalk Nation eulachon fishery on the Bella Coola River, Central Coast, BC, is provided. The majority of catches were used for making eulachon grease, a food item produced by First Nations by fermenting, then cooking the fish to release the grease. Catch statistics were kept yearly from 1945-1989 but have since, rarely been recorded. Using traditional and local ecological knowledge, catches were reconstructed based on estimated annual grease production. Run size trends were also created using local Fisheries Officers and Nuxalk interview comments. A fuzzy logic expert system was designed to estimate the relative abundance of fifteen eulachon systems. The expert system uses catch data to determine the exploitation status of a fishery and combines it with other data sources (e.g., CPUE) to estimate an abundance status index. The number of sources depended on the existing data and varied from one to eight. Using designed heuristic rules and by adjusting weighting parameters a final index was produced. Results suggest that there have been recent and extended declines in several eulachon rivers particularly the Klamath, California; Bella Coola, BC; Wannock, BC; and Kitimat, BC. Seven of the fifteen abundance time-series were used to evaluate the potential relationships between the declines and some of the factors that impact eulachon. Results suggest increases in shrimp and hake catches, seal and sea lion abundance, and sea surface temperatures were weakly associated with the declines. But contrary to expectations, adult hake biomass showed a positive association with four eulachon relative abundance time-series, suggesting that common environmental factors influenced both species. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

Nesta tese propomos o Full Bayesian Significance Test (FBST), apresentado por Pereira e Stern em 1999, para análise de modelos de misturas de normais multivariadas. Estendemos o conceito de modelos de misturas para explorar outro problema clássico em Estatística, o problema de modelos separados. Nas duas propostas, realizamos experimentos numéricos inspirados em problemas biológicos importantes: o problema de classificação não supervisionada de genes baseada em seus níveis de expressão, e o problema da discriminação entre os modelos Weibull e Gompertz - distribuições clássicas em análise de sobrevivência. / In this thesis we propose the Full Bayesian Significance Test (FBST) as a tool for multivariate normal mixture models. We extend the fundamental mixture concepts to another important problem in Statistics, the problem of separate models. In both methods, we perform numerical experiments based on important biological problems: the unsupervised classification of genes based on their expression profiles, and the problem of deciding between the Weibull and Gompertz models - two classical distributions widely used in survival analysis.

Philosophiae Doctor - PhD / This study focused on determining and understanding the needs of a group of at-risk youth in Mitchell's Plain in order to identify the social competencies and basic life skills they require to enable them to cope with their life circumstances. The first phase of this study, which adopted a qualitative framework to identify the needs of these at-risk youth, was a review of the relevant literature. This review revealed that not only is there a need to understand the transitional stage that youth find themselves in; just as important is the necessity of being aware of the political, economic and social contexts which impact on them. Focus group interviews, which are recognised as encouraging participants to reveal more than in individual interview situations, were then used to obtain the data. Thereafter, both discourse analysis and systems theory were employed to analyse the data. Thus, not only were the utterances. of the participants subjected to rigorous linguistic analysis in order to discover the subtext of what they were saying; the researcher also took cognisance of the wide range of systems which impact on youth, from the macro socio-economic levels to the micro family and school levels. these at-risk youth began to emerge. These, in turn, highlighted those affective, cognitive and behavioural skills needed by at-risk youth to optimise their future development. The analysis of the data also served to validate the assumptions contained in the working hypotheses, namely that the youths' discourses would reveal their most dominant needs. In this respect, it became apparent that socio-economic deprivation, poor educational opportunities, problematic peer and family relationships as well as intra-community violence are all underpinning issues, which contribute to the youth being vulnerable to becoming at risk. As such, these issues require urgent addressing. Furthermore, the effects of racism in post -apartheid South Africa became evident as the youths revealed the inadequacies of their current situation. The youths' discourses, thus, highlighted the economic disparities that are highly visible within their community, despite the political transformation within South Africa. The study concludes by suggesting that if a meaningful way forward is to be found, it lies in improving our understanding of how preventative intervention can effectively take place in the structural, social and interpersonal domains to provide a national programme of action for youth.

This master thesis deals with topics related to the task whether customers are able to recognize a difference between products. First, testing of equivalence and non-inferiority is discussed in detail. It is an important tool when verifying that two products are equivalent or that a new product is not substantially worse than a current product. Afterwards, Thurstone's approach is introduced as a way to evaluate the impact of a stimulus on human senses. Subsequently, using the previous chapters, there is a detailed discussion dealing with three standards wi- dely used in practice in the case when someone needs to apply sensory evaluation to verify whether customers are able to recognize a difference between products. In particular, these are duo-trio, triangle and paired comparison tests. There is a thorough explanation of their statistical base and the tests are compared accor- ding to their power. Furthermore, an approach based on the Thurstone's theory is introduced as an alternative to the standard methods. Moreover, this thesis introduces Saaty's approach to the estimation of a priority vector, which is a useful tool to compare, to order or to choose the best one from n objects. We also introduce another approach to estimation of a priority vector which is based on Saaty's idea. 1